Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 311804
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
104 PM CDT MON AUG 31 2015

.AVIATION...
FOR THE 18Z TAFS... MAIN AVIATION CONCERNS CENTER AROUND THE
TIMING OF SHOWERS AND THUNDERSTORMS AT THE TERMINALS.

AREA RADARS SHOW SCATTERED TO NUMEROUS THUNDERSTORMS GENERALLY
WEST AND SOUTHWEST OF THE HOUSTON TERMINALS EARLY THIS
AFTERNOON... WITH HIGH RESOLUTION GUIDANCE SHOWING AN INCREASE IN
COVERAGE THROUGH THE REMAINDER OF THE AFTERNOON HOURS AS THE
REGION REMAINS UNDER THE INFLUENCE OF A COMPACT MID/UPPER LEVEL
LOW. SPC MESOANALYSIS SHOWS A MOISTURE AXIS STRETCHING FROM
MATAGORDA BAY NORTH INTO CENTRAL TEXAS AND ALREADY STARTING TO SEE
A FEW CELLS DEVELOP TOWARDS CLL IN THIS CORRIDOR. IN RESPONSE...
WILL CARRY VCTS FOR ALL TERMINALS THROUGH 01Z... WITH TEMPO
AMENDMENTS LIKELY NEEDED BASED ON CONVECTIVE TRENDS. THUNDERSTORMS
HAVE BEEN CAPABLE OF ISOLATED WIND GUSTS NEAR 25 KNOTS THIS
MORNING /BYY REPORTING 27 KNOTS AT 1615Z/ AND THIS GUSTY WIND
THREAT IS EXPECTED TO CONTINUE INTO THE EVENING HOURS. LOCALLY
HEAVY RAIN MAY ALSO PROVIDE BRIEF IFR VISIBILITY RESTRICTIONS...
BUT CONFIDENCE IN OCCURRENCE AT ANY ONE TERMINAL IS TOO LOW TO
INCLUDE IN THE TAFS ATTM.

AS THE SOUTH TEXAS UPPER LOW MOVES TOWARDS THE REGION LATE
TONIGHT AND EARLY TUESDAY MORNING... SHOWER AND THUNDERSTORM
COVERAGE IS EXPECTED TO INCREASE ALONG THE COAST AND EXPAND INLAND
TOWARDS THE HOUSTON TERMINALS THROUGH MID TO LATE MORNING.
OTHERWISE... VFR CONDITIONS AND S/SE WINDS AT OR UNDER 10 KNOTS
ARE EXPECTED TO PREVAIL THROUGH THE AFTERNOON AND EVENING HOURS
OUTSIDE OF THUNDERSTORM ACTIVITY.

HUFFMAN

&&

.PREV DISCUSSION...

DISCUSSION...
UPDATED THE FORECAST THIS MORNING TO RAISE TODAY`S RAIN CHANCES...
ESPECIALLY ACROSS THE COASTAL COUNTIES AND OFFSHORE WHERE CURRENT
SHOWER AND THUNDERSTORM ACTIVITY CONTINUES TO INCREASE. WATER VAPOR
SATELLITE IMAGERY NICELY SHOWS A MID/UPPER LEVEL LOW CENTERED BETWEEN
AUSTIN AND MATAGORDA BAY...AND THIS FEATURE IN COMBINATION WITH
OUR AREA`S INCREASING PRECIPITABLE WATER VALUES IS HELPING TO
GENERATE TODAY`S STORMS. NOT SURE HOW FAR NORTHWARD THIS STUFF
WILL GO...BUT BECAUSE WE ARE ALREADY SEEING SOME ISOLATED SHOWERS
GETTING INTO LOCATIONS TO THE WEST OF BRENHAM...HAVE GONE AHEAD
AND COVERED ALL OF OUR NORTHERN COUNTIES WITH SOME LOW POPS. WOULD
NOT BE SURPRISED IF SOME SPOTS IN AND AROUND THE JACKSON-
MATAGORDA-BRAZORIA-MATAGORDA BAY AREA GET SOME RAINFALL TOTALS
APPROACHING OR EXCEEDING ONE INCH TODAY.

MODELS ARE STILL SHOWING DECREASING COVERAGE LATE THIS AFTERNOON AND
THIS EVENING FOLLOWED BY REDEVELOPMENT OVERNIGHT AND ON INTO TUESDAY
MORNING. CURRENT FORECAST HAS THIS COVERED.  42

PREV DISCUSSION...

DISCUSSION...
UPPER ANALYSIS SHOWS TROF AXIS EXTENDING FROM THE GREAT LAKES TO
ARKANSAS AND INTO S TX EARLY THIS MORNING. WATER VAPOR IMAGERY
SHOWS SHORTWAVE IN THE BASE OF THIS TROF DROPPING INTO S TX WITH
SOME LEAD DISTURBANCES EJECTING INTO THE WESTERN GULF WATERS.

SEEING SOME ISO SHRA/TSTM DEVELOPMENT IN THE MATAGORDA BAY AREA
ATTM AND WOULD EXPECT ADDITIONAL SCT ACTIVITY TO DEVELOP IN THE
NEXT COUPLE HOURS. GOES SOUNDER IMAGERY SHOWING SOME 1.7-1.9" PW`S
SITUATED 20-50NM OFFSHORE...WHICH SHOULD BE PUSHING INLAND LATER
TODAY AND ALLOW FOR SOME ISO/SCT TSTMS ACROSS SOUTHERN PARTS OF
THE REGION.

WITH THE DEEPER MOISTURE IN PLACE AND TROF AXIS NUDGING A BIT
CLOSER TONIGHT & TUE WE SHOULD SEE BETTER PRECIP CHANCES AREAWIDE
TUE & WED. TONIGHT IT SHOULD GET GOING AFTER MIDNIGHT OFFSHORE
AND SOUTH OF I-10 WITH THE AID OF SOME SPEED CONVERGENCE...AND
PROBABLY SPREAD FURTHER INLAND THRU THE DAY TUE. NEXT SHIFT OR
TWO MAY NEED TO BUMP POPS FURTHER THAN WHAT IS CURRENTLY FCST. AM
A BIT HESITANT TO GO MUCH HIGHER WELL INLAND AS HAVE BEEN BURNED
IN THESE SETUPS MANY TIMES BEFORE - WITH A LARGE COMPLEX OF PRECIP
DEVELOPING OFFSHORE ROBBING INLAND PARTS OF INFLOW, ETC AND THEY
END UP W/ NEGLIGIBLE AMOUNTS. NOT OUT OF THE REALM OF POSSIBILITY
THAT SOME COASTAL LOCATIONS SEE SOME LOCALIZED HEAVY RAIN AMOUNTS
3AM-NOON SHOULD THIS SPEED CONVERGENCE SET UP A PSEUDO BOUNDARY.
VERY LOW CONFIDENCE, BUT WORTH KEEPING AN EYE ON.

UPPER TROUGH AXIS MAKES SLOW EWD PROGRESS INTO THE MIDWEEK TIME
PERIOD...PROBABLY SITUATED ALONG THE TX/LA BORDER BY LATE WED.
PRECIP CHANCES WILL LOWER...BUT NOT GO AWAY...AS WE GET ON ITS
WESTERN PERIPHERY (MORE TYPICAL DIURNAL/SEABREEZE TYPE ACTIVITY).

MODEL CAMPS STILL SPLIT ON THE TROF/LOW MOVEMENT DURING THE
SECOND HALF OF THE WEEK. SOME CONTINUE ITS EWD PROGRESS WHILE
OTHERS RETROGRADE IT BACK INTO THE WESTERN GULF AND TOWARD
NORTHERN MEXICO & S TX. MOST HAVE BEEN SOMEWHAT CONSISTENT IN
THEIR OWN SOLNS WHICH DOESN`T HELP THINGS FORECAST-WISE. SO THRU
THE HOLIDAY WEEKEND...WILL MAINTAIN TYPICAL SCT POPS OFFSHORE
OVERNIGHT/MORNINGS THEN INLAND DURING THE AFTERNOONS. 47

MARINE...
WE SHOULD SEE A BIT MORE PCPN OVER THE COASTAL WATERS STARTING TODAY
ON THRU MUCH OF THE UPCOMING WEEK AS A BROAD UPPER LEVEL STORM
MYST- EM DEVELOPS OVER SOUTH TX. OTHERWISE NOT A LOT CHANGES WITH
THE FCST OF MAINLY LIGHT (TO OCCASIONALLY MODERATE) ONSHORE WINDS
THE REST OF THE WEEK. 41

AVIATION...
ALREADY SEEING S0ME DEVELOPMENT OVER THE COASTAL WATERS THIS MORNING
IN ASSOCIATION WITH A BROAD UPPER LEVEL STORM SYSTEM DEVELOPING OVER
SOUTH TX. WILL EXPECT THIS ACTIVITY TO WORK ITS WAY INLAND THRU THIS
AFTN...LIKELY KEEPING THE MENTION OF VCSH IN THE 12Z TAFS. ALL SIGNS
SEEM TO POINT TO A REPEAT OF THIS PATTERN FOR TOMORROW SO WILL TREND
ACCORDINGLY. 41

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      93  72  91  72  93 /  20  20  40  20  30
HOUSTON (IAH)              91  74  88  72  90 /  30  30  50  30  30
GALVESTON (GLS)            89  79  87  78  87 /  50  50  60  50  40

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

DISCUSSION...99
AVIATION/MARINE...14


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